Eruptions of the Yellowstone volcanic system have included the two largest volcanic eruptions in North America in the past few million years; the third largest was at Long Valley in California and produced the Bishop ash bed.
On the diesel Passat, the TDI badge stands for Turbocharged Direct Injection, which isn't really all that helpful as the gasoline-powered Passat is also turbocharged and also uses direct injection. Volkswagen attempts to clear this up by calling this Passat the Passat TDI Clean Diesel.
The Q7 V12 TDI is, according to Audi, the best handling Q7 due to a revised suspension, tires and brakes. Audi claims the Q7 V12 TDI can handle a lateral acceleration of over .9 g on a 300-foot (91 m) skid-pad. The concept vehicle originally appeared at the 2006 Paris Motor Show.